Light-sensitive materials comprising a light-sensitive layer containing silver halide, a reducing agent and a polymerizable compound provided on a support can be used in an image forming method in which a latent image of silver halide is formed, and then the polymerizable compound is polymerized to form the corresponding image.
Examples of said image forming methods are described in Japanese Patent Publications Nos. 45(1970)-11149 (corresponding to U.S. Pat. No. 3,697,275), 47(1972)-20741 (corresponding to U.S. Pat. No. 3,687,667) and 49(1974)-10697, and Japanese Patent Provisional Publications Nos. 57(1982)-138632, 57(1982)-142638, 57(1982)-176033, 57(1982)-211146 (corresponding to U.S. Pat. No. 4,557,997), 58(1983)-107529 (corresponding to U.S. Pat. No. 4,560,637), 58(1983)-121031 (corresponding to U.S. Pat. No. 4,547,450) and 58(1983)-169143. In these image forming methods, when the exposed silver halide is developed using a developing solution, the polymerizable compound is induced to polymerize in the presence of a reducing agent (which is oxidized) to form a polymer image. Thus, these methods need a wet development process employing a developing solution. Therefore, the process takes a relatively long time.
An improved image forming method employing a dry process is described in Japanese Patent Provisional Publications Nos. 61(1986)-69062 and 61(1986)-73145 (the contents of both publications are described in U.S. Pat. No. 4,629,676. In this image forming method, a recording material (i.e., light-sensitive material) comprising a light-sensitive layer containing a light-sensitive silver salt (i.e., silver halide), a reducing agent, a cross-linkable compound (i.e., polymerizable compound) and a binder provided on a support is imagewise exposed to light to form a latent image, and then the material is heated to polymerize within the area where the latent image of the silver halide has been formed. The above method employing the dry process and the light-sensitive material employable for such method are also described in Japanese Patent Provisional Publications Nos. 61(1986)-183640, 61(1986)-188535 and 61(1986)-228441.
The above-mentioned image forming methods are based on the principle in which the polymerizable compound is polymerized in the portion where a latent image of the silver halide has been formed.
Further, Japanese Patent Provisional Publication No. 61(1986)-260241 describes another image forming method in which the polymerizable compound in a portion where a latent image of the silver halide has not been formed is polymerized. In the method, when the material is heated, the reducing agent functions as polymerization inhibitor in the portion where a latent image of the silver halide has been formed, and the polymerizable compound in the other portion is polymerized.
According to the above image forming method, a polymer image of the polymerizable compound can be easily obtained on the light-sensitive material by utilizing high sensitivity of the photo-sensitive silver halide.
It has been noted that when the polymer in the form of an image (i.e., image relief) is cured incompletely, quality of the image decreases, that is, clearness of the image lowers, because the image made of the incompletely cured polymer is easily damaged due to its poor strength (i.e., poor hardness). Especially, when the light-sensitive material is employed as a lithographic plate, the problem of an image relief of low hardness is troublesome, because the sufficiently high hardness (to impart to the polymer image high resistance against plate wear) is required in the obtained image relief.
Various presensitized lithographic plates (referred to hereinafter as PS plate) are proposed in Japanese Provisional Publications Nos. 57(1982)-211146 and 58(1983)-16231. However, these PS plates employ a wet development process using a developing solution to prepare a lithographic plate, whereby the obtained image is apt to swell.